Wood Pellet Mill Precautions For Daily Operation, Maintenance And Use (1) - page 1

Wood Pellet Mill Precautions For Daily Operation, Maintenance And Use (1)

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1. Die clamp (No.501-0700)
(1) Correct ways of installation
① (Fig. P001) First of all, fasten one die clamp with positioning threaded hole on driving wheel, and then fasten another two die clamps on driving wheel. Lock tightly after uniform adjustment. Pay attention to: there are three uniform gaps on joint of three die clamps.
② (Fig. P002) Mark of the joint between two die clamps shall be the same (such as B-B).
③ (Fig. P003) Main screw for tightly locking die clamp shall be checked before start of machine.
④ (Fig. P004) When two die clamps clasp each other and there is almost no gap, die clamp cannot clamp dies. It indicates that die clamp has been totally worn, and it shall be replaced.
⑤ (Fig. P005) In addition, if inclined plane for installation of driving wheel is under severe wear, even new die clamp will not be tight. Therefore, driving wheel shall be replaced.
2. Grease of gearbox (Fig. P006):
With regard to SPM new pellet mill, after three-month utilization for the first time, gear oil in gearbox shall be replaced, and scrap iron on one small magnet piece in gearbox shall be cleared. Afterwards, gear oil of pellet mill shall be replaced every 2000 hours.
There is an oil level gauge (No.501-1119) for observing oil level in the bottom of one side of gearbox. When gears are not working, there is a small bubble between oil level and the top of oil level gauge; when gears are running, oil level shall be at the middle of oil level gauge.


3. Lubrication of main shaft bearing (No.501-0307) and roller bearing (No.521-02S2)
(1) Before starting pellet mill, operator shall inject grease to roller at first until grease overflows from shaft collars on two ends of roller, which can indicate that roller is full of grease. Then, pellet mill shall be started for 2 hours operation. Turn off the pellet mill after 2 hours operation, and open cover of it; operator shall wear protective eyewear for fear that grease will spill out and hurt personnel. Inject grease to roller again until roller is full and record quantity of grease and time. In this way, we can Picture out proper quantity of adding grease and time for every 2 hours through practice.
(2) (Fig. P007) When pellet mill is in continuous production, add oil lubrication from three copper grease fittings (No.: 501-0324) on shaft collars in the middle of safety housing. Copper grease fittings on two sides are used for adding oil to two rollers, and the copper grease fitting in the middle is used for adding oil to bearing of main shaft. When producing biomass wood pellet in accordance with proper oil quantity and time, add grease (30-40g/ piece-time) to roller every 2 hours (animal feed: 4 hours); add grease (40-50g/ time) to bearing of main shaft every 4 hours (animal feed: 8 hours).
(3) (Fig. P008 and P009) If operator find oil leakage as shown in picture during adding oil, grease cannot be injected into roller and main shaft bearing, thus, bearing will be damaged due to the lack of oil.
(4) (Fig. P010 and P011) Operator shall adjust thickness of sealed paper pad (No.: 501-0313) (1-3 pieces 1mm) in shaft collars of main shaft, and tighten up screw in case of oil leakage. Check screw (No.: 501-0310) constantly and tighten it.


4. Proper installation of main shaft gland (No.501-0308) and belleville spring (No.: 501-0312)
(1) (Fig. P012 and P013) Before pellet mill leaves factory, workers of wood pellet mill have installed about 6 pieces (5-7 pieces) belleville springs of right quantity and direction (Fig. P013) in gap in accordance with size of gap between end of main shaft and main shaft gland.
(2) In change of belleville spring every year, operator shall replace it in strict accordance with quantity and direction of pictures above. Random change is not allowed. When operator tightens two screws (No.:
501-0310) to fasten main shaft gland, about 0.5 mm gap shall be reserved between those belleville springs (5-7 pieces). When there is difficulty in pelleting, main shaft will have about 0.5 mm gap for elastic move, which is functioned as protection of equipment.
(3) Operator shall check whether screw (No.: 501-0310) and grease fitting (No.: 501-0324) of main shaft gland is tightened every week; if operator finds that shake of main shaft is abnormal during operation of pellet mill, especially the production of pellet which is difficult to produce such as wood pellet and cattle feeds, screw of main shaft gland may be loose during shaking, it shall be tightened up.

5. Correct installation way of shear pin (No.: 521-04S9 or 501-0409)
(1) (Fig. P014) Groove of safety pin shall be in the middle of gap between tooth profile flange (No.: 501-0407) and safety housing (No.: 501-0401); in this way, when die and roller is stuck and main shaft drives tooth profile flange to shift, shear pin can be cut from groove of shear pin and it can be functioned as protection for pellet mill. Proper installation of shear pin is shown in Fig. P014.
(2) (Fig. P015) In operation of pellet mill, sometimes, retaining clips (No.: 501-0410) on two ends of shear pin are not installed, and it leads to dislocation of shear pin, and groove are not in the middle of gap between tooth profile flange and safety housing; when main shaft drives spline flange to shift under state of emergency, safety pin cannot be cut. Thus, main shaft or drive system of pellet mill will be damaged. As shown in Fig. P015, safety pin has been dislocated and in improper position.
(3) After a period of time for using shear pin bushing (No.: 501-0408), if operator find that inner bore of shear pin bushing is under severe wear and shear pin is easy to be in bore, lining of shear pin shall be replaced. In this way, shear pin can normally play a protective role.

6. Cause of main shaft (No.521-03S1 or 0301) and quill shaft (No.521-05S0 or 0500) quivering
When the main shaft is correctly and properly installed, suspend the main shaft end cap (NO.501-0308) tightly. The 5 to 7 belleville springs (NO.501-0312) on the gland are pressed with a gap of only about 0.5mm. The gap between the tooth form end of the main shaft and the tooth profile flange base shall be small they shall match tightly. At this time, if the operator loosens the compression roller assembly, (Fig. P0106) uses a peeler to pry the head of the main shaft in the die, the head of the main shaft will not move.
Thus, when the pellet mill makes pellet, the head of the main shaft will not quiver and can provide maximum pressure to squeeze the materials out of the die. The function is especially evident when such materials hard to granulate as sawdust and rice hull granule are squeezed out. If the main shaft quivers and retreats, granulating pressure will decrease obviously; at the normal working gap between the die and the roller, the granulation  is inefficient  with  hard  granule  output  and  obvious decrease  of  capacity.  In  this case, the operator will generally adopt the wrong method of tightening the roller against the working zone in the inner wall of the die. Though this method can steady the output temporarily, working zones of roller and the die can be seriously damaged (as shown in Fig. P017) in short time, which causes poorer quality and capacity of granules and greatly shortened service life of die and the roller.

A good operator will find out the reason why the head of the main shaft quivers and solves the problem completely:
(1) Fastening screws of the safety housing are loose.
Solution: the operator takes off the tooth profile flange, checks if the 12 (6) screws and spring cushions are sound, changes the broken screws and then fastens the screws (as shown in Fig. P018).
(2) Two fastening screws of the main shaft are loose.
Solution: fasten the screws (as shown in Fig. P011).
(3) The gap between the tooth profile flange and the end of the main shaft is a little loose for the equipment has been used for a long time (as shown in Fig. P019).
Solution: because the safety housing assembly comprises the safety housing and the tooth profile flange that work together, the operator should replace the safety housing assembly with new one.
(4) The bearing of the main shaft has been damaged due to wear or burned out due to oil break. Solution: the operator should change the bearing of the main shaft (No.501-0307).
(5) Decentraction of the quill shaft leads to the quivering of the main shaft. Solution: change the quill shaft.
(6) The head of the main shaft and the pressing plate comprise the main shaft assembly. One taper locating pin positions the pressing plate at the head of the main shaft to ensure the two roller assemblies concentric with the main shaft. If the operator turns the pressing plate for 180 and installs it on the head stand of the main shaft wrongly, the two compression rollers will not be concentric with the main shaft; thus, the die will strike the roller at this moment and separate from it at that moment, which damages the equipment. Solution: the operator accurately finds the locating hole, installs the locating hole of the pressing plate on the head stand of the main shaft correctly, blows in the taper locating pin and then fastens the pressing plate with two screws tightly (as shown in P020).
(7) The bearing of the roller has been worn, resulting in waggle of the outer shell of the roller, which will add to difficulty to the granulating. Solution: the operator should change the worn bearing several days before the bearing is damaged; thus, the roller shell and inner parts will not be damaged and can be used several times (as shown in Fig. P021).
(8) The wear ring of the die has been worn and the inner size is relatively big, which causes the dies to retreat during its working when it is compressed, thus being hard to granulate. Solution: the operator changes the wear ring of the die (as shown in Fig. P022).

(9) Each time the operator changes the die and installs it, after operating for two or three hours, the die clamp screw will be partial loose; the die clamp will not hold the die tightly; the die will shake, making it difficult to granulate. The solution: each time after the operator changes the die and makes it operate for two to three hours, the operator shall stop it and lock the die clamp screw tightly again to make sure that the die clamp holds the die tightly.
(10) After the damage of the front large bearing (No.501-0507) or the back bearing (No.501-0508) of the quill shaft, when the die is pried by iron rod, it will shake and the pressure of granulation will decrease significantly, making it difficult to granulate. The solution: the operator changes the damaged bearing.
(11) The front and back bushings (No.521-03S3/03S2) of roller in the main shaft hole have been worn and the hole is enlarged, causing that the compression roller shakes and leaks grease in the work and grease can not be added to the roller. The solution: the operator changes the bushings (Fig.P023/P024). In addition, O circle of the SPM520S die shall be sheathed to avoid oil leakage (as shown in Fig. P024A), and lever principle shall be used to facilitate the installation of roller assembly (as shown in Fig. P024B).


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